How do desert plants survive?

In deserts,the temperature in the day can rise above 45 degrees celcius.As most deserts are  found near the equator the temperature range can be very extreme. As it is very hot, animals are rarely found there and minimal plants survive in the desert.So, how do desert plants survive?

The most essential need for a plants is water,as sunlight ,oxygen and carbon dioxide are abundant.In the desert, there is hardly any rainfall. Even though sunlight is always recieved in the desert,there is no water for evaporation,thus the water cycle cannot occur.Thus, there is only minimal life found in the desert.

Plants use water that has been stored in soil pores.in dry areas plants naturally tend to grow some distance apart,giving each of them a cahnce to tap water from a large area when there is no rain.Plants that grow naturally in areas with a drought have two ways of coping with dry soil.Many plants have long roots that sink deep into the soil and sometimes into the aquifer below. Other plants spread out huge nets of roots through the soil and thus gather moisture from a wide area.Plants can also stop water from evaporating from their leaves(they are deciduous).They have thick waxy leaves with very few pores that reduce the amount of water evaporated during transpiration. Some plants also have thin needle-like leaves that reduce the surface area of the leaf thus reducing the amount of water loss during tranpiration.

Plants also can adapt to dry areas by behaviorial adaptations. Desert plants could also have developed a lifestyle in conformance with the seasons of greatest moisture and/or coolest temperatures.These type of plants are usually (and inaccurately) referred to as perennials, plants that live for several years, and annuals, plants that live for only a season.Desert perennials often remain dormant during the hot and dry periods of the year.When water is available, they would then start growing.Most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.They also have drought -resistant seeds, that would remain dormant until the dry period is over.


Xerophytes are plants that change their physical structure to adapt to the environment to reduce the amount of water loss during tranpiration. Desert xerophytes such as cactus, are among the most drought-resistant plants on the planet due to their absence of leaves, shallow root systems, ability to store water in their stems, spines for shade and waxy skin to seal in moisture.Cactus plants can also photosynthesise using their stem in subsitute of its leaves.Its leaves are spiny .long and narrow to reduce the amount of water loss during transpiration.

Phreatophytes, like the mesquite tree, have adapted to desert conditions by developing extremely long root systems to draw water from deep underground near the water table. The mesquite's roots are considered the longest of any desert plant and have been recorded as long as 80 feet.

The Creosote Bush is one of the most successful of all desert species because it utilizes a combination of many adaptations. Instead of thorns, it relies for protection on a smell and taste wildlife find unpleasant. It has tiny leaves that close their stomata during the day to avoid water loss and open them at night to absorb moisture.
 
Some perennials, such as the Ocotillo, survive by becoming dormant during dry periods, then springing to life when water becomes available. After rain falls, the Ocotillo quickly grows a new suit of leaves to photosynthesize food. Flowers bloom within a few weeks, and when seeds become ripe and fall, the Ocotillo loses its leaves again and re-enters dormancy. This process may occur as many as five times a year. The Ocotillo also has a waxy coating on stems which serves to seal in moisture during periods of dormancy.


Annuals
Contrary to the usual idea that deserts are uniformly hot, dry and homogeneous in their lack of plant life, they are actually biologically diverse. Each season's unique precipitation pattern falls on a huge variety of mini-environments.

Desert plants must act quickly when heat, moisture and light inform them it's time to bloom. Ephemerals are the sprinters of the plant world, sending flower stalks jetting out in a few days. The peak of this bloom may last for just days or many weeks, depending on the weather and difference in elevation. 

Links to very interesting videos about desert plants:
http://www.youtube.com/watch?v=UkqfIQ6I-6I
http://www.youtube.com/watch?v=jlaMBqS88EA&feature=related


Plants found in deserts:Joshua tree,Cacti,Palm trees,Yuccas.

Sources: the living world(book);http://www.desertusa.com/du_plantsurv.html

pressure in everyday life

This is just a topic so i can fill up my blog.(JOKING)
Did you know that when you are showering pressure is involved?
Did you know when you are typing your blog you are applying pressure?
Did you know that when your head is supported by your hand while daydreaming you're applying pressure?
Well ,pressure is around you more than you know it.
In the shower head ,there is a valve where you can control the amount of water flowing through.The higher the pressure the harder it would beat down against your skin.
While you are typing your finger is applying pressure unto the keys ,thus it would send information to the computer and display the words you are typing .
When your head is upon your hand ,you are putting pressure on the hand ,the pressure from the hand would then be transferred to the elbow while it is resting in the table.Well, you cannot do this for too long as your hand will get numb due to lack of blood circulation and the teacher will catch sooner or later

Pressurization in aircraft cabins

HI this is just a link about the pressurization in aircraftshttp://en.wikipedia.org/wiki/Cabin_pressurization

Harmful pressure

Though stiletto heels may make you look glamourous and tall there are hidden harms of it .It may cause you your foot,back and even toes.

                                                     These seemingly harmless shoes are actually harmful.

These small stud like heels have a very small surface area on the bottom causing the weight of one to be all supported by that puny stick.These shoes are not meant for walking but for looks only ,however many wear it for the sake of vanity.

As you walk, your unusually highly elevated foot will start to feel uncomfortable.Most ignore it but they are going to regret it once they are feeling back pains .because of the preesure forced on the foot it would slwy start to affect the spine causing to curve slowly.Though most do not feel it at first ,the eventual result would be horrifying.

Stiletto heels are to make you taller but if you wear if for a very long time,you're curved back would make you shorter.!

Due to the small sharp edges of most stiletto heels, your toes would be compressed inside. As the toenail grows,the toe nail would mould to the shape of the edge,causing toe nail to cut into the skin of your toe .This would hurt no matter where you walk.Obviously ,the disadvantages outweigh the advantages.

DON'T WEAR STILETTOS! 

Renewable energy

There many forms of renewable energy such as wind energy and solar energy

Here are the link to the video

http://www.youtube.com/watch?v=oIU5fFmDeSc

The energy that we are mainly consuming is non-renewable energy , though these ways we are using them may be convenient for us but itis harming us the most,

Pressure video mythbusters

http://www.youtube.com/watch?v=JmJoyuUJj2Q
This is a video on how deadly pressure can be.the pressure in the water heater was so great that the remaining part of the rocketed into the sky.Pressure has many factors, in this case HEAT.

Static & Dynamic Equlibrium

http://www.rwc.uc.edu/koehler/biophys/2h.html--- Static Equilibirum
http://dl.clackamas.edu/ch105-03/dynamic.htm--- Dynamic Equilibrium

Force and moments

The turning effect to accomplish a task is called the moment of a force.
The principle of moments state :When a body is in equilibrium, the sum of clockwise moments about the pivot is equal to the sum of anticlockwise momenra about the same pivot.
To calculate the moment of a force : M=F x D(perpendicular distance from the pivot to the line of action of the force.)
Note : work done is calculated by :F x Parallel distance
The S.I. unit of moments is Nm(Newton metre)

In the picture on the above,to calculate the effort needed,take the weight of the load and mulitply it with the distance from the load to the pivot then divide it by the distance of the pivot to the effort

In this second class lever above ,multiply the distance from the load to the pivot with the weight of the load .Divide the result with the distance between the load and effort.

For the third class lever,mutlitply yhe weight of the load and the distance o the load to the effort.Then,use the result and divide it by the distance of the effort to the pivot.

Force & work

To be considered work done, there must be...
-a force acting on the object
-the object moves
-the movement of the object is in the same direction of the force

Work is measured in J(joules)
One joule is the amount of work done when a force of one newton moves an object by one metre in the direction of the force.
W=F x s
No work is done when ...
-the object does not move
-the object is perpendicular to the force
here is a video on work done:http://www.youtube.com/watch?v=IvcOYOO0Fvw&feature=related

Pressure

The S.I. unit of pressure is N/m2.
Pressure =Force /area
Pressure can be also call Pascal. 1000Pa=1kPa\
To find force,mass x gravitaional field strength = ~~~~N
To find area , length x breath = ~~~~m2
When the force decreases,the pressure decreases.
When the area increases, the pressure decreases.
One can lie on a bed of nails without getting injured as...
-the area of the bed of nails is significant
-thus the weight of the person is significantly less and the pressure would be very little.

Weight & Mass

Weight is a measurement of the gravitational force acting on an object.

Mass is the measure of the amount of matter in an object.

(e.g.weight x gravitational field strength =mass)

(50kg x 10 =500N)
Weight is usually measured with spring balances while mass is usually measured using a lever-like system using counterweights.

Forces

It is either a push or a pull exerted by one object on another.(E.g.Gravitational force, Frictional force ,Magnetic force, Elastic force, Squeezing force, Stretching force , Folding force ,Twisting force.)
S.I. Unit For force is Newton(N)
Extension/Compression Spring balance can be used to measure force.
Force can ...
-Move a stationery object
-Change the speed of a moving object
-Change the shape and size of an object
-Change the direction of an object
-Stop a moving object

Archimedes heat ray

The 2nd century AD author Lucian wrote that during the Siege of Syracuse (c. 214–212 BC), Archimedes destroyed enemy ships with fire. Centuries later, Anthemius of Tralles mentions burning-glasses as Archimedes' weapon. The device, sometimes called the "Archimedes heat ray", was used to focus sunlight onto approaching ships, causing them to catch fire.

This purported weapon has been the subject of ongoing debate about its credibility since the Renaissance. René Descartes rejected it as false, while modern researchers have attempted to recreate the effect using only the means that would have been available to Archimedes. It has been suggested that a large array of highly polished bronze or copper shields acting as mirrors could have been employed to focus sunlight onto a ship. This would have used the principle of the parabolic reflector in a manner similar to a solar furnace.

A test of the Archimedes heat ray was carried out in 1973 by the Greek scientist Ioannis Sakkas. The experiment took place at the Skaramagas naval base outside Athens. On this occasion 70 mirrors were used, each with a copper coating and a size of around five by three feet (1.5 by 1 m). The mirrors were pointed at a plywood mock-up of a Roman warship at a distance of around 160 feet (50 m). When the mirrors were focused accurately, the ship burst into flames within a few seconds. The plywood ship had a coating of tar paint, which may have aided combustion.

In October 2005 a group of students from the Massachusetts Institute of Technology carried out an experiment with 127 one-foot (30 cm) square mirror tiles, focused on a mock-up wooden ship at a range of around 100 feet (30 m). Flames broke out on a patch of the ship, but only after the sky had been cloudless and the ship had remained stationary for around ten minutes. It was concluded that the device was a feasible weapon under these conditions. The MIT group repeated the experiment for the television show MythBusters, using a wooden fishing boat in San Francisco as the target. Again some charring occurred, along with a small amount of flame. In order to catch fire, wood needs to reach its flash point, which is around 300 degrees Celsius (570 °F).

When MythBusters broadcast the result of the San Francisco experiment in January 2006, the claim was placed in the category of "busted" (or failed) because of the length of time and the ideal weather conditions required for combustion to occur. It was also pointed out that since Syracuse faces the sea towards the east, the Roman fleet would have had to attack during the morning for optimal gathering of light by the mirrors. MythBusters also pointed out that conventional weaponry, such as flaming arrows or bolts from a catapult, would have been a far easier way of setting a ship on fire at short distances.

Reference:http://en.wikipedia.org/wiki/Archimedes

Cartesian Diver

The Cartesian Diver works because the pressure you impose on the closed
system compresses the air in the bottle (water does not compress), including the
air in the diver (whether it be in a condiment packet or in a modified eye dropper).
The compression of the air makes it more dense because you are forcing the
amount of air in the bottle (and diver) into a smaller space. In order for your diver
to sink, the density of the diver needs to become greater than the density of
water. The more dense the air becomes, the further the diver will sink.

Boyle’s Law: P1V1=P2V2 is also applied in this experimaent
relationship of pressure and volume of an ideal gas (constant temperature and
quantity)

Submarines

Diving and Surfacing


­A submarine or a ship can float because the weight of water that it displaces is equal to the­ weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down. Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.

To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air .When the submarine is on the surface, the ballast tanks are filled with air and the submarine's overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks. In addition, the submarine has movable sets of short "wings" called hydroplanes on the stern (back) that help to control the angle of the dive. The hydroplanes are angled so that water moves over the stern, which forces the stern upward; therefore, the submarine is angled downward.

To keep the submarine level at any set depth, the submarine maintains a balance of air and water in the trim tanks so that its overall density is equal to the surrounding water (neutral buoyancy). When the submarine reaches its cruising depth, the hydroplanes are leveled so that the submarine travels level through the water. Water is also forced between the bow and stern trim tanks to keep the sub level. The submarine can steer in the water by using the tail rudder to turn starboard (right) or port (left) and the hydroplanes to control the fore-aft angle of the submarine. In addition, some submarines are equipped with a retractable secondary propulsion motor that can swivel 360 degrees.

When the submarine surfaces, compressed air flows from the air flasks into the ballast tanks and the water is forced out of the submarine until its overall density is less than the surrounding water (positive buoyancy) and the submarine rises. The hydroplanes are angled so that water moves up over the stern, which forces the stern downward; therefore, the submarine is angled upward. In an emergency, the ballast tanks can be filled quickly with high-pressure air to take the submarine to the surface very rapidly.



Reference:http://science.howstuffworks.com/submarine1.htm

Fruits Float Experiment

Is it true that an orange floats in water ?Or does it sink?What happens when the orange is peeled?These homemade videos and still photos show it all!

Physics lesson 3.3.1(Density)

Density is calculated by mass per unit volume.

For example,syrofoam is less dense than wood .and wood is less dense than aluminium.

Density also affect the buoyancy of an object.

Physics lesson 3.2.1(mass)

Mass is a measure of the amount of matter in a body
The mass of the Oasis of the Sea is about 100,000 t.

The mass of an average airplane is 164t .

This is a picture showing how Bernoulli's principle works.

This allows planes to take off even when it is so heavy.

Archimedes

Archimedes may have used his principle of buoyancy to determine whether the golden crown was less dense than solid gold.The most widely known anecdote about Archimedes tells of how he invented a method for determining the volume of an object with an irregular shape. According to Vitruvius, a new crown in the shape of a laurel wreath had been made for King Hiero II, and Archimedes was asked to determine whether it was of solid gold, or whether silver had been added by a dishonest goldsmith. Archimedes had to solve the problem without damaging the crown, so he could not melt it down into a regularly shaped body in order to calculate its density. While taking a bath, he noticed that the level of the water in the tub rose as he got in, and realized that this effect could be used to determine the volume of the crown. For practical purposes water is incompressible, so the submerged crown would displace an amount of water equal to its own volume. By dividing the weight of the crown by the volume of water displaced, the density of the crown could be obtained. This density would be lower than that of gold if cheaper and less dense metals had been added. Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!" (Greek: "εὕρηκα!," meaning "I have found it!")

The story of the golden crown does not appear in the known works of Archimedes. Moreover, the practicality of the method it describes has been called into question, due to the extreme accuracy with which one would have to measure the water displacement .Archimedes may have instead sought a solution that applied the principle known in hydrostatics as Archimedes' Principle, which he describes in his treatise On Floating Bodies. This principle states that a body immersed in a fluid experiences a buoyant force equal to the weight of the fluid it displaces. Using this principle, it would have been possible to compare the density of the golden crown to that of solid gold by balancing the crown on a scale with a gold reference sample, then immersing the apparatus in water. If the crown was less dense than gold, it would displace more water due to its larger volume, and thus experience a greater buoyant force than the reference sample. This difference in buoyancy would cause the scale to tip accordingly. Galileo considered it "probable that this method is the same that Archimedes followed, since, besides being very accurate, it is based on demonstrations found by Archimedes himself."
Reference :http://en.wikipedia.org/wiki/Archimedes#The_Golden_Crown

Physics lesson 3.1 (measuring volume)

Using a measuring cylinder as well as a Eureka can ,enables us to find the volume of irregular solids.
Measuring Cylinder
1.Fill the measuring cylinder to a certain height and record it
2.Suspen the irregular solid into the measuring cylinder
3. Record the final water level and subtract the initial level from it
4.the Equation is the volume of the irregular solid
Eureka Can
1. Fill water till the mouth of the spout
2. Suspen the irregular solid into the can
3. The amount of water displaced in the measuring cylinder is the volume of the irregular solid

Yawning

http://www.yourdiscovery.com/video/mythbusters-top-10-is-yawning-contagious/
A video on yawning

http://www.howstuffworks.com/question572.htm
A article explaining about yawning

Physics lesson 2.3 (measuring volume)

To measure the volume of the liquids we can use the measuring cylinder ,burette or the pipette.
Meniscus
In narrow glass cylinders, the liquid is curved into a shape called a meniscus.
Meniscus can be either a concave or a convex.A concave meniscus occurs when the molecules of the liquid is attracted to the container more than to each other.(e.g.water)Conversely,A convex meniscus occurs when the liquid molecules have stronger attraction yo each other than to the container.(e.g.mercury)
Surface tension
This is caused by cohesion(the attraction of molecules to other molecules)
To read the accurate volume, ensure that your eye level is the same as the bottom of the meniscus curve.

Physics lesson 2.3 (Measurement of Area& Volume)

Area

Only tick a box if more than half of it is shaded

Volume

LIQUIDS:Using the measuring cylider ,burette and pipette ,we can measure the volume of the liquids

Physics lesson 2.2 [Vernier Calipers (Zero Error)]

Zero error is when the jaws of the vernier calipers are fully closed ,and the zero marking on the vernier scale does not coincide with the zero marking on the main scale .

When the zero marking on the vernier scale is on the right of the main scale, it is called a positive zero error.To calculate the accurate measurement, subtract the zero error from the original reading.

When the zero marking on the vernier scale is on the left of the main scale ,it is called a negative zero error .To calculate the accurate measurement, add the zero error from the original reading.

Physics lesson 2.1 (Vernier Calipers)

Vernier Calipers are used to measure short lenghts and diameters of objects of up to 10 cm.
They consist of the outside jaws ,inside jaws ,main scale reading ,vernier scale reading and the taill.
Using the vernier calipers :
1. Close the jaws of the vernier calipers . Ensure that the zero marking on the vernier scale is in line with the zero marking on the main scale.
2.Place the object within the jaws of the vernier calipers and clamp it firmly in place.
3.Read the length

Physics lesson 2(Vernier Calipers)

Vernier Calipers

Physics lesson 1(Measurement of units)

Q: Why does metres have to be metres and not any other unit?
A:Metres is used as it is internationally recogninsed thus it would avoid confusion.
Elaboration:Metre is the SI base unit of distance .Originally,the meter was designed to be one-tenth of a quadrant the distance between the equator and the north pole . For a long time ,the metre was precisely defined as the length of an actual object, a bar kept at the International Bureau of Weights and Measurements in Paris.In recent years,however,the SI base units (with one exception) have been redefined in abstract terms so they can be reproduced to any desired level of accuracy in a well equipped laboratory.